1. Field of the Invention
The present invention relates to a hearing aid for hearing-impaired persons having a first microphone arrangement with directional characteristics, and a second microphone arrangement.
2. Description of the Prior Art
A hearing aid having first and second microphone arrangements is described in German OS No. 22 22 543. This hearing aid includes a first microphone arrangement having a directional reception pattern consisting of two microphones disposed at the wrist of a hearing-impaired person such that the respective directions of maximum signal reception of the two microphones are parallel to each other, preferably in the direction of an extended finger. This hearing aid also includes a second microphone arrangement consisting of a single microphone for omni-directional reception which is secured to the wrist between the two microphones of the directional microphone arrangement. The second microphone arrangement is disposed such that its reception direction is predominately perpendicular to the surface of the hand. A switching element permits the hearing-impaired person to switch between the general omni-directional reception and reception from a preferred direction. The microphone for omni-directional reception can also be utilized in combination with the earpiece of a telephone apparatus.
A hearing aid having two frontal microphones and two side microphones disposed in the proximity of the ears of a user is described in U.S. Pat. No. 3,789,163. The frontal microphones are not directional microphones. The microphones disposed in the proximity of the ears simply function to increase the sensitivity of the overall microphone arrangement at the sides for improving three-dimensional hearing. This system could not be used, for example, with the omni-directional microphones of German OS No. 22 22 543 because if such microphones were arranged close to the ears of the user in this system the desired directional characteristic of the overall arrangement would be destroyed, particularly in the higher frequency range.